Recently, particularly from about 1970, emission control for automobiles has been seriously considered. Accordingly, a law regulating automobile exhaust gas emission was promulgated to the effect that the passenger automobiles must be equipped with a device for purifying the exhaust gas. Several systems were proposed for devices for purifying the exhaust gas, but the most widely used at present is a catalyst converter system, whereby HC and CO are oxidized and, simultaneously, NOx is reduced. The structure of these catalyst converters is such that a carrier, which is a honeycomb sintered body of ceramic mainly composed of corderite, is mounted in a metallic cylinder, as a metallic substrate, and porous .gamma.-Al.sub.2 O.sub.3 powder, which is impregnated with a noble metal (Pt.about.Pd) catalyst, is deposited on the carrier. The honeycomb ceramic has, however, disadvantages in that it is not highly resistant to mechanical impact, some exhaust gas is able to leak through the clearance between the honeycomb and the outer sleeve, and in addition, the exhaust resistance is rather high. To cope with these disadvantages, Japanese Unexamined patent publication No. 57-71898 disclosed a several tens of microns thick foil rolled from high Al ferritic stainless steel laminated with a corrugated sheet which is produced by forming the foil, or coiled in the form of a honeycomb, thereby enabling it to be used as the carrier instead of the ceramic honeycomb mentioned above. Japanese Unexamined patent publication No. 56-96726 also disclosed how to produce a foil used for the metal honeycomb by peeling a high Al ferritic stainless steel bar. Since a high degree of working strain during the peeling is introduced into the stainless steel foil produced by this method, when the foil is heated to a high temperature in an oxidizing atmosphere, the diffusion of Al from the interior to the surface of the foil is promoted, which results in the formation of Al.sub.2 O.sub.3 in the form of whiskers, which enhances a rigid bonding of .gamma.-Al.sub.2 O.sub.3 powder, i.e., the direct carrier of a noble metal-catalyst, on the honeycomb. Nevertheless, these techniques have several disadvantages, in that, in the former method, in a cold-rolling process to obtain an approximately 40 to 50 .mu.m thick foil of high Al stainless steel, the annealing and pickling steps must be repeated several times because of the poor workability of the high Al stainless steel, and after assembly as a honeycomb, the foils must be fixed together by brazing as well as to an outer sleeve by a complicated process, which leads to an increase of costs.
Also for the peeling technique, it is difficult to stably obtain a foil having a uniform thickness and width.
Therefore, it has been desired to develop a simpler means in the method for producing a metallic substrate used for an automobile exhaust gas purifying device.